Telephone-exchange system



C. B. FOWLER. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JAN-2, 19I8.'

Patented Feb. 10,1920.

MFA

' UNITED STATES PATENT OFFICE.

CLARENCE B. FOWLER, 0F NEW YORK, N. Y., ASSIG-NOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, 0F YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Feb. 10, 1920.-

Application filed January 2, 1918. Serial No. 209,966.

To all whom it may concern:

Be it known that I, CLARENCE B. FOWLER,

a citizen of the United States, residing at New York, in the county of New York, State of New York, have invented certain new and useful Improvements in Telephone- EXcha-nge Systems, of which the following is a full, clear, concise, and exact description. This invention relates to telephone exchange systems and more particularly to such systems of the control energy type in which both local and rural subscribers lines terminate at the same central. ofiice, the former being equipped for both common battery signaling and talking, and the latter for common battery signaling and local bat tery talking.

It is an object of the present invention to provide improved signaling means for sys-v tems of this character. i In accordance with one feature of this invention, a link circuit for interconnecting telephone lines of the types mentioned is provided with two relays one of which operates upon connection with a rural subscribers lineand cooperates with a supervisory or subscriber controlledrelay for con trolling a supervisory signaling device, and the other of which. operates upon connection with a local subscribers line and cooperates with the supervisory relay to control the supervisory signaling device. 7

. For a more complete understanding of this invention, reference should be had to the following description considered in connection with the accompanying drawing illustrating one embodiment thereof.

As shown in the drawing, a local telephone line A extends to and may bejconnected in any well known manner with a cord circuit C, the calling end of which is equipped with apparatus for carrying-into eflect the purposes of this invention. The calling end of this cord circuit may connect with either a rural subsc'ribers line B or a local subscribers line D. A local subscribers line is one which is equipped for both common battery signaling and talking, while a rural subscribers line is equipped for common battery signaling, and local battery talking. The cut-off relay of the rural line is of high resistance so that a marginal relay associated with the link circuit will not respond cuit of the relay 10.

1 upon connection with the rural line, but will operate when connection is made with the local line which has a cut-off relay of low.

resistance. It is thought that this invention may be best understood from a description of the operation of the system disclosed in the drawing and it will be so described.

Subscriber A having initiated a call and the cord circuit C having been connected therewith, the operator actuates the listen-- ing key 5 to connect the telephone set with the calling line. The operator upon being advised that connection is desired With a local subscribers line, for example line D, restores the listening key 5 to normal posi tion and inserts calling plug 6 into. line jack 7 of line D. Relays 8, 9 and10 of the cord circuit and cut-oil relay 11 of line D are thereupon operated over a circuit from battery through the lower Winding of relay 8, the winding of relay 10, the winding of marginal relay 9, the upper Winding of relay 8, sleeve contacts of the plug 6 and the jack 7 and winding of the cut-ofi relay 11 to ground. While relay 10 operates to establish a circuit for the supervisory lamp 12, this circuit is only maintained for an instant and is of-no effect, for the marginal relay 9 operates at the same time as relay 10 and in so doing opens the energizing cir- Marginal relay 9 thereupon establishes a locking circuit for itself from battery through the supervisory lamp 12, upper alternate contact and winding of relay 9, the upper winding of relay 8, sleeve contacts of the plug 6 and jack 7 and the winding of the cut-ofi relay 11 to ground. The supervisory lamp 12- is thereupon lighted. Relay 8, in operating, closes its contacts, theclosure ofthe upper contact extending the tip of the calling plug to a contact of ringing-relay 13. The operation of the cut-ofi relay 1'1 disconnects the thereupon energized over the circuit from battery through the winding of ringing relay 13, normal contact of relay 25, normal'contact of trip relay 16, contact'of relay 15, lower normal contact of relay 14 and lower contact of relay 14 and lower contact of relay 8 to ground. Ringing relay 13, in operating, connects ringing current to line D over a circuit from the source of ringing current through the winding of trip relay 16, lower alternate contact of ringing relay 13, ring contacts of the plug 6 and the j ack7 over one side of the line, through the usualcall bell connected with the line at the station of line D, back over the other side of the line, tip contacts of" the jack 7 I and plug 6, upper contact of relay 8, and

for the contact of relay 15 and the lower upper-alternate cont-act of ringing relay 13 to ground. A portion of this ringing current passes through condenser 21. which bridges the now open lower normal contact ofringing relay 13 and then passes through a winding of the repeating coil, whereupon a ringing indication is transmitted to the calling party. Y

The called subscriber in responding to the operation of the call bell removes the receiver from the switch hook, thereby causing the operation of trip 16 which opens its contact, removing the short circuit from the winding of relay 25. Relay 25' thereupon operates, establishing a temporary locking circuit for itself through its left-hand alternate contact, and, in so doing, estab lishes a short circuit for the ringing relay 13. Ringing relay 13 thereupon releases its armatures, disconnecting ringing current from the line and closing its normal contacts which are in the talking circuit. Relay 25 in operating also causes the operation of'relay 14 over the circuit from battery through the winding thereof, and the right-hand contact of relay 25 to ground. Relay 14 in operating closes the contact in the ring talking strand of the cord circuit 0,

opens the energizing circuits of relays 15 and- 25, and establishes a locking circuit for itself through its lower alternate contact and the lower contact of relay 8 to ground. The release of relay 25does not complete an energizingcircuit for the ringing relay 1.3

normal contact of relay 14 are now open. Supervisory relay 22 is operated upon the closure of the upper alternate contact of relay-14 and in operating establishesa shunt circuit about the lamp 12 which includes the resistance 23, thereby extinguishing this lamp.

At the conclusion of the conversation, restoration of the receiver to the switchhook by subscriber causes the release of supervisory relay 22, whereby the shunt circuit of the lamp isopened and the lamp is lighted to furnish the disconnect signal.

The operator may thereupon withdraw the and 10 of the cord circuit and cut-ofl? relay 31 of'the line circuit. The supervisory lamp 12 is lighted by the operation of relay 10. Marginal relay 9 does not operate, due to the high resistance of the winding of the cut-off relay 31. Upon the operation of relay 8, relay 14'operates over a circuit from battery through the winding of relay 14, the lower normal contact of marginal relay 9, lower normal contact of relay Y14 and the lower contact of relay 8 to ground. Relay 14 in operating establishes a circuit con nection between a ringing key 32 and. the rural line B so that upon the actuation of the ringing key 32, ringing current from the source 33 is connected to line B. The two sources of ringing current 20 and 33 may be and in practice usually are the same alternating current generator. Relay 14 in operating also establishes for itself the hereinbefore traced locking circuit. Upon the response of the called subscriber, supervisory relay 22 is operated to extinguish'the supervisory lamp 12 in the manner herein before described.

From the above description, it will be understood that when connection is made with a rural line, relay 10 functions to cause the supervisory lamp 12 to light, and supervisory relay 22 subsequently responds to extinguish this. lamp. Therefore, when connection is made with a rural line, these two relays cooperate to control the supervisory lamp. When connection is made with the local line, however, relay 9 re-- sponds to cause the lighting of the supervisory lamp, andthe same supervisory relay 22 later responds to extinguish the lamp. Therefore, when connection is made with a localline, relay 9 then cooperates with the same supervisory relay to control the supervisory lamp. I

I What is claimed is 1. A telephone eXchange system comprising local and rural subscribers lines, a link circuit for interconnecting the lines, a signaling device in the link circuit, electromagneticineans'in the link circuitresponsiVe to the connection thereof with the rural subscribers line to cause the operation of the signaling device, an electromagnetic switching device in the link'circuit responsive to the connectionthereof with a local subscribers line for operating the signaling device, and means controlled overa line of either character for stopping the operation of the signaling device.

2. A telephone exchange system comprising local and rural subscribers lines, a link circuit for interconnecting such lines, a signal lamp in the link circuit, means in the link circuit responsive to the connection thereof With the rural subscribers line to light the signal lamp, means in the link circuit responsive to the connection thereof with a local subscribers line for lighting the signal lamp, a relay in the link circuit controlled over a line'pf either character for extinguishing the signal lamp.

3. A telephone exchange system comprising local and rural subscribers telephone lines, a link circuit for interconnecting the lines, a supervisory signal lamp in the link circuit, a local circuit relay in the link circuit responsive to the connection thereof With a rural subscribers line for lighting the lamp, a second local circuitrelay in the linkv circuit responsive to the connection thereof With the local subscribers line for lighting the lamp,a'nd a supervisory relay 7 in the link circuit controlled over a line of either character for extinguishing the lamp. In Witness Whereof I hereunto subscribe i my name this 28th day of December A. D.,

, CLARE-NOE B. FOWLER. 

